How much gold would you have if you stole every bit that's ever been mined? Not much—you'd be able to make a cube of solid gold with 60-foot sides. There just isn't that much gold in the world, and it's getting harder and harder to find it. In fact, our love of gadgets may be part of the problem.

In a report from theWall Street Journal this morning, we learn that we're only two decades away from exhausting the world's gold supply if mining continues apace. How could we be running out of gold? It's simple. As gold boomed in the 90s and 00s, the easy-to-access deposits were sapped of their supplies. Now, the gold being discovered is way deeper into the Earth, which means that discovering it takes a lot more work before it can be extracted.

In 1995, 22 gold deposits with at least two million ounces of gold each were discovered, according to SNL Metals Economics Group. In 2010 there were six such discoveries, and in 2011 there was one. In 2012: nothing.

Unless gold companies want to dig deeper—often in arctic areas that are notoriously difficult to mine—it's becoming difficult to discover the low-hanging (or high-hanging, in this case) fruit. In one instance quoted in the story, miners had to blast away 100 metric tons of rock to find just an ounce of the good stuff. It's contributing to illegal mining practices, too.

An aerial photo shows tailings in La Pampa district produced by informal mining in Peru's Madre de Dios region in Peru. AP Photo/Rodrigo Abd.

Sure, a gold cube with 60-foot sides sounds massive. But think about chiseling that block into all the gold bars, coins, electronic components, and even jewelry that exists in the world. It's actually extremely small—there's only .005 parts per million in the Earth's crust, compared to 50 parts per million of copper. In fact, some gold experts say we have even less: In 2013, Warren Buffet estimated that the cube would only have sides of 20 feet in length.

Here's where things get really strange. As the BBC points out, all of the gold mined since the beginning of time has, in essence, been recycled: A piece of gold mined by the Romans may have been melted down into a gold bar in the 1800s, say, and may have eventually made its way into a consumer product like a gold watch.

But all those gadgets and computers and electronics that require minute amounts of gold to function? They're changing that gold reuse pattern for the first time in history. Because so little gold is used in this tech, it doesn't make sense to recycle it. So while gold, like air, has remained a static resource on Earth, that's no longer true. Our gold resources will continue to deplete, one iPhone at a time. [Wall Street Journal, BBC]